Offensive schemes: Phil Jackson.
Defensive schemes: Gregg Popovich (though it's more of a two way tie between him and Riley).
In game adjustments: Gregg Popovich.
Rotations: This is a wash. I don't know if it's ever possible to measure, all of them have had great rotations and have made mistakes in the playoffs.
Developing young talent: Don't know if this is more of a by-product of a great front office or specifically defining an appropriate role for a player, but seems like this is Popovich's.
Managing egos: Has to be Phil, no doubt. Other guys weren't even in the similar situations.
Adjusting to aging rosters: Also a wash.
Calling plays out of a time out in crucial situations:Gregg Popovich, hand down.